Barium oxide

Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.

An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O^2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al₂O₃ that protects the foil from further oxidation.

Manganese dioxide is the inorganic compound with the formula MnO
_². This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
_² is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery. MnO
_² is also used as a pigment and as a precursor to other manganese compounds, such as KMnO
_⁴. It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO
_² has an α-polymorph that can incorporate a variety of atoms in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
_² as a possible cathode for lithium-ion batteries.

Barium nitrate is the inorganic compound with the chemical formula Ba(NO₃)₂. It, like most barium salts, is colorless, toxic, and water-soluble. It burns with a green flame and is an oxidizer; the compound is commonly used in pyrotechnics.

Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula PbO. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components. It is an amphoteric oxide.

Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity into two or more fragments. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction.

Thermal decomposition, or thermolysis, is a chemical decomposition of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reaction. Thermal decomposition is a chemical reaction where heat is a reactant. Since heat is a reactant, these reactions are endothermic meaning that the reaction requires thermal energy to break the chemical bonds in the molecule.

Copper chromite often refers to inorganic compounds with the formula Cu₂Cr₂O_x. They are black solids. Cu₂Cr₂O₄ is a well-defined material. The other copper chromite often is described as Cu₂Cr₂O₅. It is used to catalyze reactions in organic chemistry.

A uranate is a ternary oxide involving the element uranium in one of the oxidation states 4, 5 or 6. A typical chemical formula is M_xU_yO_z, where M represents a cation. The uranium atom in uranates(VI) has two short collinear U–O bonds and either four or six more next nearest oxygen atoms. The structures are infinite lattice structures with the uranium atoms linked by bridging oxygen atoms.

Zinc peroxide (ZnO₂) appears as a bright yellow powder at room temperature. It was historically used as a surgical antiseptic. More recently zinc peroxide has also been used as an oxidant in explosives and pyrotechnic mixtures. Its properties have been described as a transition between ionic and covalent peroxides. Zinc peroxide can be synthesized through the reaction of zinc chloride and hydrogen peroxide.

Samarium(III) oxide (Sm₂O₃) is a chemical compound. Samarium oxide readily forms on the surface of samarium metal under humid conditions or temperatures in excess of 150°C in dry air. Similar to rust on metallic iron, this oxide layer spalls off the surface of the metal, exposing more metal to continue the reaction. The oxide is commonly white to off yellow in color and is often encountered as a highly fine dust like powder.

Barium peroxide is an inorganic compound with the formula BaO₂. This white solid is one of the most common inorganic peroxides, and it was the first peroxide compound discovered. Being an oxidizer and giving a vivid green colour upon ignition, it finds some use in fireworks; historically, it was also used as a precursor for hydrogen peroxide.

Barium chlorate, Ba(ClO₃)₂, is the barium salt of chloric acid. It is a white crystalline solid, and like all soluble barium compounds, irritant and toxic. It is sometimes used in pyrotechnics to produce a green color. It also finds use in the production of chloric acid.

Barium ferrate is the chemical compound of formula BaFeO₄. This is a rare compound containing iron in the +6 oxidation state. The ferrate(VI) ion has two unpaired electrons, making it paramagnetic. It is isostructural with BaSO₄, and contains the tetrahedral [FeO₄]²⁻ anion.

Manganese(II) oxide is an inorganic compound with chemical formula MnO. It forms green crystals. The compound is produced on a large scale as a component of fertilizers and food additives.

Metal peroxides are metal-containing compounds with ionically- or covalently-bonded peroxide (O²⁻
₂) groups. This large family of compounds can be divided into ionic and covalent peroxide. The first class mostly contains the peroxides of the alkali and alkaline earth metals whereas the covalent peroxides are represented by such compounds as hydrogen peroxide and peroxymonosulfuric acid (H₂SO₅). In contrast to the purely ionic character of alkali metal peroxides, peroxides of transition metals have a more covalent character.

Caesium superoxide is a chemical compound with the chemical formula CsO₂. It consists of caesium cations Cs⁺ and superoxide anions O−2. It is an orange solid.